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  Java Practices -> Validate email addresses
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<div class='page-title'>Validate email addresses</div>

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<br>When a user inputs an email address, it may be validated by passing
it to the constructor of <tt><a href="http://java.sun.com/javaee/5/docs/api/javax/mail/internet/InternetAddress.html">InternetAddress</a></tt>.
If it does not comply with RFC822, then a checked exception will be thrown.
<p>Note that a simple local address, such as <tt>"joe"</tt>, complies with
RFC822. If this type of address is undesired, then some extra validation
will be needed.

<p><b>Example</b>

<p>Here is a class that validates email
addresses through the static method <tt>isValidEmailAddress</tt>. Note
that it treats local addresses as invalid (as implemented by the call to
<tt>hasNameAndDomain</tt>).
<br>
<PRE>

<span class='keyword'>package</span> hirondelle.web4j.util;

<span class='keyword'>import</span> java.util.regex.*;
<span class='keyword'>import</span> javax.mail.internet.AddressException;
<span class='keyword'>import</span> javax.mail.internet.InternetAddress;
<span class='keyword'>import</span> javax.servlet.http.HttpServletRequest;
<span class='keyword'>import</span> javax.servlet.http.HttpServletResponse;
<span class='keyword'>import</span> javax.servlet.http.HttpSession;

<span class='comment'>/**
* Static convenience methods for common web-related tasks.
*/</span>
<span class='keyword'>public</span> <span class='keyword'>final</span> <span class='keyword'>class</span> WebUtil {
  
  <span class='comment'>/**
  * Validate the form of an email address.
  *
  * &lt;P&gt;Return &lt;tt&gt;true&lt;/tt&gt; only if 
  *&lt;ul&gt; 
  * &lt;li&gt; &lt;tt&gt;aEmailAddress&lt;/tt&gt; can successfully construct an 
  * {@link javax.mail.internet.InternetAddress} 
  * &lt;li&gt; when parsed with "@" as delimiter, &lt;tt&gt;aEmailAddress&lt;/tt&gt; contains 
  * two tokens which satisfy {@link hirondelle.web4j.util.Util#textHasContent}.
  *&lt;/ul&gt;
  *
  *&lt;P&gt; The second condition arises since local email addresses, simply of the form
  * "&lt;tt&gt;albert&lt;/tt&gt;", for example, are valid for 
  * {@link javax.mail.internet.InternetAddress}, but almost always undesired.
  */</span>
  <span class='keyword'>public</span> <span class='keyword'>static</span> <span class='keyword'>boolean</span> isValidEmailAddress(String aEmailAddress){
    <span class='keyword'>if</span> (aEmailAddress == <span class='keyword'>null</span>) <span class='keyword'>return</span> <span class='keyword'>false</span>;
    <span class='keyword'>boolean</span> result = <span class='keyword'>true</span>;
    <span class='keyword'>try</span> {
      InternetAddress emailAddr = <span class='keyword'>new</span> InternetAddress(aEmailAddress);
      <span class='keyword'>if</span> ( ! hasNameAndDomain(aEmailAddress) ) {
        result = <span class='keyword'>false</span>;
      }
    }
    <span class='keyword'>catch</span> (AddressException ex){
      result = <span class='keyword'>false</span>;
    }
    <span class='keyword'>return</span> result;
  }

  <span class='keyword'>private</span> <span class='keyword'>static</span> <span class='keyword'>boolean</span> hasNameAndDomain(String aEmailAddress){
    String[] tokens = aEmailAddress.split(<span class='literal'>"@"</span>);
    <span class='keyword'>return</span> 
     tokens.length == <span class='literal'>2</span> &amp;&amp;
     Util.textHasContent( tokens[<span class='literal'>0</span>] ) &amp;&amp; 
     Util.textHasContent( tokens[<span class='literal'>1</span>] ) ;
  }
  
  <span class='comment'>//..elided
</span>}
 
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<div class='topic-section'>See Also :</div>
<div class='main-body'>
 
  
  <a href='TopicActionc3f2-2.html?Id=179'>Send trouble-ticket emails</a> <br>
 
  
  <a href='TopicAction5f31-2.html?Id=188'>A Web App Framework - WEB4J</a> <br>
 
  
  <a href='TopicAction9163-2.html?Id=242'>Launch other applications</a> <br>
 
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